JPH1158230A - Dressing device of grinding tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dress a hemispherical tool by making it come into contact with a gel coating inclusive of abrasive grains formed in a formed positive electrode, as relatively rotating a grinding tool and this formed electrode. SOLUTION: A formed negative electrode 26 is opposedly installed in a recess 20a of a positive electrode hold-down member 20 at an opposite minute interval δto a formed electrode 18. A desired d.c. voltage or current is impressed to a gap between the formed electrode 18 and the formed electrode 26. When an electrode field is formed in a grinding fluid in space between the electrode 18 and the electrode 26, a surface of the formed electrode 18 attracts abrasive grains by an electrophoretic phenomenon. Therefore, the abrasive grains are hydrophobicly adsorbed on a surface of the electrode 18, forming a gel coating being high in grain density. In this state intact, a ball grinding wheel 30 is dressed by making it come into contact with the gel coating formed on the surface of the electrode 18, as rotating this ball grinding wheel 30 and the electrode 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dressing apparatus for a grinding tool, and more particularly to a dressing apparatus for dressing a hemispherical grinding tool with high accuracy.

[0002]

2. Description of the Related Art In order to mirror-finish a free-form surface of a mold by performing a displacement cutting method, a grindstone or a grinding tool containing ultrafine diamond abrasive grains formed into a hemisphere has been used. The grindstone is deformed by the progress of the grinding process, in which fine chips removed from the work surface are clogged between the abrasive grains on the grindstone surface, and the abrasive grains and the binder (matrix) of the grindstone are gradually removed. In this case, in order to create a high-precision machined surface, the grinding stone must be accurately truing (forming) and dressing (sharpening).
There is a need to.

As a precise surface polishing method, a polishing method utilizing the electrophoresis phenomenon has been already known. For example, Japanese Patent Publication No. 59-46739 discloses a method of grinding a work surface by electrophoresis. In this method, in a suspension in which free abrasive grains are dispersed, the workpiece and the polisher are opposed to each other, and are rotated relative to each other while applying a voltage between them. I do. Further, JP-A-8-257912 discloses that
An in-process dressing method using electrophoresis for regenerating a grindstone while simultaneously polishing a work in a suspension in which free abrasive grains are dispersed is disclosed.

[0004]

As described above, it is indispensable to perform truing and dressing with high precision in high-precision grinding. However, the methods disclosed in the above two publications cannot perform truing and dressing of a hemispherical grinding tool. An object of the present invention is to provide an apparatus capable of accurately truing and dressing a grinding tool, particularly a grinding tool made of a hemispherical grindstone, utilizing the electrophoresis phenomenon.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to provide a grinding tool and a positive electrode having a predetermined voltage between the positive electrode and the negative electrode while rotating the grinding tool and the positive electrode correspondingly in the polishing liquid. Alternatively, it is achieved by dressing a grinding tool by applying a current and adsorbing free abrasive grains in the polishing liquid to the positive electrode by the electrophoresis phenomenon.

According to the present invention, there is provided a dressing apparatus for a grinding tool, wherein a hemispherical grinding tool rotatably supported in a processing tank storing a polishing liquid, a rotating axis of the grinding tool provided opposite to the grinding tool. A positive electrode having a shape that is rotatably supported about a rotation axis parallel to the grinding tool, and that has a shape corresponding to the grinding tool; An electrode, forming an electric field between the positive electrode and the negative electrode, causing an electrophoretic phenomenon of free abrasive grains dispersed in the polishing liquid therebetween, and the grinding tool. A dressing apparatus for a grinding tool for performing relative dressing of the grinding tool and the general-purpose positive electrode to dress the grinding tool.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a dressing apparatus 10 for a grinding tool according to an embodiment of the present invention includes
A hollow cylindrical frame 14 is provided on an upper surface of the processing tank 1, and a processing tank 1 for storing a polishing liquid in the frame 14 is provided.
6 is attached. An anode fixing member 20 is rotatable around a rotation axis O in the processing tank 16.
4 is supported. The anode fixing member 20 is formed of an electrically insulating material such as acrylic into a substantially cylindrical shape having a concave portion 20a.
b. Flange portion 20b of anode fixing member 20
A sealing member 14 such as an O-ring
a is provided to prevent the polishing liquid from entering the inside of the frame 14.

In the present embodiment, the polishing liquid comprises carboxymethyl cellulose (CMC) in ion-exchanged water and a suspension in which alumina oxide abrasive grains are dispersed as free abrasive grains. A polishing liquid having a relatively high viscosity was used in order to prevent the polishing liquid from being scattered by centrifugal force and to disperse alumina abrasive grains having a relatively large particle diameter in the polishing liquid. More specifically, about 5% by weight of alumina abrasive grains were dispersed in the CMC aqueous solution, and the viscosity was maintained at 45 to 50 cP. The particle size of the alumina abrasive was 1.5 to 6.7 μm. A polishing liquid circulation device 24 is provided to circulate the polishing liquid in the processing tank 16. The polishing liquid circulation device 24 is provided with a tubing pump 24a. The tubing pump 24a sucks the polishing liquid from the bottom of the processing tank 16 through a pipe 24b, and the processing tank 1 through a pipe 24c.
6, specifically, the anode fixing member 2 in the processing tank 16.
The polishing liquid is circulated over the upper part of the recess 20a.

In the recess 20a of the anode fixing member 20, a positive electrode 18 is fixed concentrically to the anode fixing member 20 along the rotation axis O. The positive electrode 18 is formed of a corrosion-resistant metal material such as stainless steel, for example, to a grinding tool that performs truing and dressing. That is, it is formed into a rotating body shape as shown in the figure having an arc having a radius substantially equal to the hemispherical portion of the grinding tool. A drive motor 22 for rotating and driving the anode fixing member 20 about the rotation axis O is fixed on the upper surface of the base 12 inside the frame 14, and the anode fixing member 20 is connected to a rotation shaft 22 a of the drive motor 22. Attached to. The drive motor 22 is, for example, 1500 rpm
Can be rotated. In this way, the total positive electrode 18
Is driven to rotate about the rotation axis O together with the anode fixing member 20 by the drive motor 22.

In the recess 20 a of the anode fixing member 20, a negative electrode 26 is further formed with a small gap δ with respect to the positive electrode 18.
It is opposed. The general negative electrode 26 is made of, for example, graphite and is formed in a general shape with respect to the general positive electrode 18. The small gap δ is fixed to a fixed portion (not shown) of the dressing device 10 so as to be adjustable. A desired DC voltage or DC current is applied between the positive electrode 18 and the negative electrode 26 by the power supply 28. An electric field is formed in the polishing liquid between the positive electrode 18 and the negative electrode 26.

In the recess 20a of the anode fixing member 20, a ball grindstone 30 is further provided as a grinding tool to be trued or dressed. Ball whetstone 30
Is a rotation axis O1 parallel to the rotation axis O of the shaped positive electrode 18.
Is attached to the front end of the spindle device 32 so as to be rotatable around the center. The spindle device 32 is configured to be movable in a direction along the rotation axis O1 and in a direction perpendicular to the rotation axis, so that the tip of the ball grindstone 30 can be accurately positioned with respect to the overall positive electrode 18. ing. Ball whetstone 3
0 is an extremely fine resin-bonded grindstone having an average particle size of 4 to 5
μm diamond abrasive grains are combined with a melamine resin and formed in a shape combining a cylinder and a hemisphere. The ball grindstone 30 may be simply formed in a hemispherical shape.

Hereinafter, the operation of the embodiment of the present invention will be described.
Generally, when alumina abrasive grains are dispersed in an aqueous solution in which CMC is dissolved, the hydrophilic groups of CMC release metal ions and become negatively charged, and the abrasive grains are adsorbed to the hydrophobic groups. When a voltage is applied between the positive electrode 18 and the negative electrode 26 to form an electric field in a minute gap between the positive electrode 18 and the negative electrode 26, a polishing liquid comprising a suspension in which abrasive grains are dispersed in a CMC solution is formed. The abrasive grains that have been hydrophobically adsorbed are attracted to the surface of the positive electrode 18 by the electrophoresis phenomenon. Then, C sucked on the surface of the
The MC and the abrasive grains are hydrophobically adsorbed on the surface of the positive electrode 18, and as shown in FIG.
Is formed.

When the positive electrode 18 and the ball grindstone 30 are pressed against each other while rotating in this state, the shape of the positive electrode 18 is transferred to the ball grindstone 30 and the ball grindstone 30 is trued (formed). Is done. The ball grindstone 30 is dressed by bringing the ball grindstone 30 into contact with the gel-like film 34 formed on the surface of the molded positive electrode 18 while rotating the ball grindstone 30 and the shaped positive electrode 18. You. That is, ball grinding stone 3
0 is pressed into contact with the surface of the positive electrode 18 to remove both the diamond abrasive grains of the ball grindstone 30 and the melamine resin as a binder. Is transferred. Also, the ball grinding wheel 30 is not the general positive electrode 18 but the general positive electrode 18.
By positioning the ball grindstone 30 so as to come into contact with the gel-like film 34 formed on the surface of the ball, the gel-like film acts as a polisher, and only the melamine resin of the ball grindstone 30 is removed and the ball grindstone 30 is dressed. Is done.

According to an experiment, when the ball grinding stone 30 is brought into contact with the shaped anode 18 by 15 μm using 1.5 μm alumina abrasive grains and the applied current is 1 A, the ball is rounded to a circularity of about 0.8 μm. The grinding stone could be trued. Also, a ball grinding stone 30 using 1.5 μm alumina abrasive grains is used.
When a gap of 5 μm is set between the electrode and the positive electrode 18 and the applied current is set to 1 A, it is observed that the abrasive grains are hardly removed from the ball grindstone 30 and that good dressing is performed. Was. In addition, this dressing device,
A grinding tool may be mounted on the table of a machining center that processes a die or the like by mounting it on the main shaft so as not to hinder processing, and dressing or truing may be performed on-machine as needed during die processing. Alternatively, it may be configured as a dressing-only machine.

[0015]

According to the present invention, a gel-like film containing abrasive grains is formed on the surface of the positive electrode by forming an electric field in the polishing liquid in which free abrasive grains are dispersed and electrophoresing the abrasive grains. Using the film, the grinding tool is brought into contact with the surface of the positive electrode while the hemispherical grinding tool and the positive electrode are rotated relative to each other. The dressing of the grinding tool can be performed by making contact only with the film formed on the surface of the positive electrode. Therefore, a hemispherical grinding tool can be accurately formed and sharpened. In particular, in the dressing, so-called soft dressing in which only the bond is removed without causing the abrasive grains of the grinding tool to fall off as much as possible can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a dressing device according to an embodiment of the present invention.

FIG. 2 is a partially enlarged view of the shaped positive electrode, showing a film formed on the surface of the shaped positive electrode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Dressing apparatus 12 ... Base 14 ... Frame 16 ... Processing tank 18 ... Shape positive electrode 24 ... Abrasive circulating device 26 ... Shape negative electrode 28 ... Power supply device 30 ... Ball grindstone

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobuyuki Tsukijihara 1-3-8 Kaneuki, Kokuraminami-ku, Kitakyushu-shi, Fukuoka Prefecture Room 22 Murakami Heights Room 204

Claims (2)

[Claims] 1. A dressing device for a grinding tool, comprising: a hemispherical grinding tool rotatably supported in a processing tank in which a polishing liquid is stored; a hemispherical grinding tool provided opposite to the grinding tool, and parallel to a rotation axis of the grinding tool. A positive electrode having a shape corresponding to the grinding tool and rotatably supported around a rotation axis, and a fixed negative electrode opposed to the general positive electrode at a predetermined interval and fixed. Forming an electric field between the positive electrode and the negative electrode, causing an electrophoretic phenomenon of free abrasive particles dispersed in the polishing liquid between the two, and the grinding tool and the A dressing device for a grinding tool for dressing the grinding tool by relatively rotating the positive electrode. 2. The dressing apparatus according to claim 1, wherein the dressing apparatus further includes a polishing liquid circulation device for circulating a polishing liquid in the processing tank.